In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on semiconductor wafers (“wafers”). The wafers include integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.
During plasma processing the confinement ring or set of parallel rings surrounds a plasma etch chamber to prevent the plasma from spreading beyond the etch chamber to the larger vacuum chamber. Generally, these rings are designed to allow gas to flow through to the vacuum chamber while preventing the diffusion of plasma. The configuration is often used in conjunction with polymerizing plasma chemistries, which may be needed for selective etching of films or for deposition of films. Such polymers may be hydrocarbons, fluorocarbons and/or hydrofluorocarbons in composition, and may also include nitrogen, oxygen, silicon, aluminum, molybdenum, titanium, tantalum, copper, cobalt, or tungsten. The deposition of polymeric films on plasma etch chamber surfaces may be desirable in some case or detrimental in others. Regardless, there is often a need to remove the polymer films from the etch chamber surfaces after each plasma etching operation to maintain stable and unchanging reactor conditions throughout a production cycle.
Conventional methods to remove these films involve striking an in-situ cleaning plasma in the etch chamber when the wafer is not present. However, removing polymer films from the confinement ring(s) is often problematic. It is well known that most of the polymer deposition on the confinement rings is found at the inner diameter surfaces of these rings. Typically, the length of time required for in-situ cleaning is determined by the relatively inefficient removal rate of polymer films from the confinement ring(s). The other polymer-coated surfaces within the reactor may be fully cleaned by a significantly shorter exposure to the in-situ cleaning plasma. As a result of the relatively inefficient cleaning of the confinement rings, the cleaning process times may be longer than desired which reduces the throughput of the plasma etch chamber, ultimately adding to the cost and cycle time for producing the integrated circuit devices. To further complicate matters, in-situ cleaning often results in the premature erosion of expensive plasma etch chamber parts such as the electrostatic chuck and the upper electrode panel.
In view of the forgoing, there is a need for a rapid in-situ cleaning method, apparatus, or system that is effective at removing polymer films from plasma confinement rings while minimizing erosion of the other plasma etch chamber components.